Abu Ayyub radhiyallāhu relates…

Abu Ayyub radhiyallāhu relates that he heard the Messenger of Allah sallallahu alyhi wasallam saying, “He who fasts in Ramadhan and then follows it with six fasts in Shawwal will be as though he fasted all the time. (Muslim)

Thauban radhiyallāhu relates that he heard the Messenger of Allah sallallahu alyhi wasallam saying, “Allah Ta’ala made a single good deed equivalent to ten the like thereof, so one month is equivalent to ten months, and six days of fasting after the Eid-ul-Fitr completes one year. (Nasai)

Imam Nasai Rahimahullah and Ibn Khuzaimah rahimahullah have recorded that fasting in the month Ramadhan is equivalent to ten months and fasting six days is equivalent to two months. This totals the reward of fasting for one full year. (Nasai)